Hey guys! Ever wondered how those super addictive online games are made? Today, we're diving into the world of game development by recreating the classic game Slither.io using Scratch! Scratch is an awesome visual programming language perfect for beginners, and by the end of this article, you'll have your very own version of the snake-eating-dots game. Let's get started!

Setting Up the Stage and the Snake

First things first, let's talk about setting up our Scratch project. This involves creating the stage where all the action happens and, of course, designing our slithery snake. We'll start with a blank canvas and build from there, step by step. So, fire up Scratch and let's get coding!

Creating a New Scratch Project

Alright, open up Scratch! If you're new to this, head over to the Scratch website and click on "Create" to start a new project. You'll see the Scratch interface, which is pretty user-friendly. On the left, you have your blocks of code; in the middle, the scripting area where you drag and drop those blocks; and on the right, the stage where your game will play out.

Let's delete the default cat sprite – we won't need it for our Slither.io game. Click on the trash can icon next to the cat sprite in the bottom right corner. Now, our stage is empty and ready for us to add our snake!

Designing the Snake Sprite

Now, for the star of our game: the snake! We need to create a new sprite for it. Click on the "Choose a Sprite" button in the bottom right corner (it looks like a cat head). You can either upload an image of a snake, draw one yourself using the Scratch paint editor, or choose a simple shape like a circle. For simplicity, let's go with a circle. Select the circle shape, choose a color you like for your snake (maybe a vibrant green or blue?), and draw a small circle in the center of the paint editor.

Once you've drawn your circle, make sure to center it properly. Use the crosshair tool to grab the circle and drag it until the center of the circle aligns with the crosshair in the editor. This ensures that the snake rotates correctly later on. Rename your sprite to "Snake Head" – this will help you keep track of things as your project grows. Great job! You've just created your snake's head. This is the most important part.

Initializing the Snake

Now that we have our snake head, we need to initialize it, meaning setting its starting position, direction, and size. This is done using code blocks. Drag the "when green flag clicked" block from the Events category to your scripting area. This block ensures that the following code runs when you click the green flag, which starts the game.

Next, let's set the snake's starting position. Drag a "go to x:0 y:0" block from the Motion category and attach it to the "when green flag clicked" block. This will place the snake in the center of the stage at the beginning of the game. Then, add a "point in direction 90" block from the Motion category to make the snake start by moving to the right. Finally, adjust the size of the snake using a "set size to %" block from the Looks category. A size of 50% or 60% usually works well.

Your code should now look something like this:

when green flag clicked
 go to x: 0 y: 0
 point in direction 90
 set size to 60 %

Congratulations! You've set up the stage and created your snake sprite. Now, let's move on to making the snake move and adding some interactive elements to our Slither.io game.

Making the Snake Move and Adding Controls

Alright, now that we have our snake, we need to make it move! This involves writing code that continuously updates the snake's position based on user input. We'll use the arrow keys to control the snake's direction. Let's dive into the code!

Implementing Basic Movement

To make the snake move continuously, we'll use a "forever" loop. Drag a "forever" block from the Control category to your scripting area. Inside this loop, we'll add code to move the snake forward. Drag a "move (10) steps" block from the Motion category and place it inside the "forever" loop. This will make the snake move 10 steps in its current direction continuously.

However, just moving forward isn't enough. We need to control the snake's direction. We'll use the arrow keys for this. Drag four "when key pressed" blocks from the Events category to your scripting area. Set these blocks to "when right arrow key pressed", "when left arrow key pressed", "when up arrow key pressed", and "when down arrow key pressed".

Adding Directional Controls

Now, let's add the code to change the snake's direction when the arrow keys are pressed. For the "when right arrow key pressed" block, drag a "point in direction (90)" block from the Motion category and attach it. For the "when left arrow key pressed" block, attach a "point in direction (-90)" block. For the "when up arrow key pressed" block, attach a "point in direction (0)" block, and for the "when down arrow key pressed" block, attach a "point in direction (180)" block.

Your code should now look something like this:

when green flag clicked
 forever
 move (10) steps

when right arrow key pressed
 point in direction (90)

when left arrow key pressed
 point in direction (-90)

when up arrow key pressed
 point in direction (0)

when down arrow key pressed
 point in direction (180)

Test your game by clicking the green flag. You should be able to control the snake's movement using the arrow keys. If the snake is moving too fast or too slow, adjust the number of steps in the "move (10) steps" block. This is where you can customize how the game plays. Experiment with different speeds to find what feels best. Now your snake should respond to your every command!

Creating the Snake's Body and Food

No Slither.io game is complete without a growing snake body and food for it to eat! Let's tackle these next. We'll start by creating clones of the snake's head to form the body and then add food sprites that the snake can consume to grow longer. Here's how we do it.

Cloning the Snake's Body

To create the snake's body, we'll use clones. Clones are copies of a sprite that can act independently. First, we need to create a variable to keep track of the snake's length. Go to the Variables category and click on "Make a Variable". Name it "Snake Length" and click "OK".

Set the initial value of "Snake Length" to 5 (or any number you prefer) when the green flag is clicked. Add a "set [Snake Length] to (5)" block from the Variables category to your "when green flag clicked" script. Now, we'll create clones of the snake's head to form the body. Add a "create clone of [myself]" block from the Control category to the end of the "when green flag clicked" script.

To make the clones act as the snake's body, we need to add code to the "when I start as a clone" block. From the Control category, drag a "when I start as a clone" block to your scripting area. Inside this block, we'll add code to make the clone follow the snake's head. Add a "go to [Snake Head]" block from the Motion category to make the clone move to the snake's head's position.

To create the trailing effect of the snake's body, we need to delay the movement of each clone. Use a "repeat (Snake Length)" loop and move the "go to [Snake Head]" block inside. Before the go to block add a "move (1) steps" block, the complete code in the loop should be "move (-1) steps" and "go to [Snake Head]" block. This setup creates the illusion of a growing snake as the clones follow each other. Ensure that at the end of the clone's behavior, the clone deletes itself to avoid filling memory by adding a "delete this clone" block from the Control category.

Adding Food for the Snake

Now, let's add food for the snake to eat. Click on the "Choose a Sprite" button again and select a simple shape like a circle or a star. Choose a different color from the snake to make the food easily distinguishable. Rename this sprite to "Food".

To make the food appear randomly on the stage, use the "go to random position" block from the Motion category. Add a "when green flag clicked" block from the Events category and attach a "forever" loop from the Control category. Inside the loop, add a "go to [random position]" block. This will make the food continuously jump to random locations on the stage.

To detect when the snake eats the food, we'll use the "touching" block from the Sensing category. Add an "if (touching [Snake Head]) then" block from the Control category inside the "forever" loop. Inside the "if" block, add code to increase the snake's length and move the food to a new random position. Increase the "Snake Length" variable by 1 using a "change [Snake Length] by (1)" block from the Variables category. Also, add a "go to [random position]" block to move the food to a new location. This is crucial for the snake to grow.

Adjusting Snake Length

To actually make the snake grow visually, you'll need to adjust the cloning code to account for the increased "Snake Length". Modify the "when I start as a clone" script by using the "Snake Length" variable to control how far back each clone spawns from the head. This will make the snake appear longer as it eats more food. This part is very important.

Adding Game Over and Scoring

To complete our Slither.io game, we need to add a game-over condition and a scoring system. The game should end if the snake collides with itself, and we should keep track of the player's score based on how much food they've eaten. Let's implement these features.

Implementing Game Over Condition

The game should end if the snake collides with its own body. To detect this, we'll add code to check if the snake's head is touching any of its body clones. Go to the "Snake Head" sprite and add a new "forever" loop inside the "when green flag clicked" script. Inside this loop, add an "if (touching [Snake Head]) then" block from the Control category. In the condition part, use "touching Sprite1" from sensing and select the Snake Head sprite.

Inside the "if" block, add code to stop the game. Use the "stop [all]" block from the Control category. This will halt all scripts and effectively end the game. Additionally, you can add a message to the screen indicating that the game is over. Create a new sprite called "Game Over" and add text that says "Game Over". Hide this sprite at the beginning of the game and show it when the snake collides with itself. This makes the game look and feel more polished. This is critical for the game.

Adding a Scoring System

To add a scoring system, we'll create another variable called "Score". Go to the Variables category and click on "Make a Variable". Name it "Score" and click "OK". Set the initial value of "Score" to 0 when the green flag is clicked. Add a "set [Score] to (0)" block from the Variables category to your "when green flag clicked" script.

Whenever the snake eats food, we'll increase the score. Go to the "Food" sprite and add a "change [Score] by (1)" block from the Variables category inside the "if (touching [Snake Head]) then" block. This will increase the score by 1 each time the snake eats food.

To display the score on the screen, drag a "[Score]" block from the Variables category to the stage. This will show the current score in the top left corner of the screen. You can also customize the appearance of the score by adding a label next to it, such as "Score: ".

Polishing the Game and Adding Extra Features

Now that we have a fully functional Slither.io game, let's add some extra features and polish it up to make it even more enjoyable. Here are a few ideas:

Adding Speed Boost

Implement a speed boost feature that allows the player to temporarily increase the snake's speed. You can use a key press (such as the space bar) to activate the speed boost. When the key is pressed, increase the number of steps in the "move (10) steps" block for a short period. After the speed boost duration, return the speed to normal.

Adding Multiple Food Items

Instead of having just one food item, add multiple food items that appear randomly on the stage. This will make the game more dynamic and challenging. You can create clones of the "Food" sprite and have them appear at different locations.

Improving Graphics and Sound

Enhance the game's graphics by using custom images for the snake and food. You can also add sound effects for eating food and game over. This will make the game more visually and aurally appealing.

Adding a High Score

Implement a high score system that saves the highest score achieved by the player. You can use variables and file operations to save and load the high score. This will add a competitive element to the game.

By following these steps, you can create a fun and engaging Slither.io game using Scratch. Experiment with different features and customizations to make the game your own. Happy coding!

Conclusion

Creating a Slither.io game in Scratch is a fantastic way to learn the basics of game development. You've learned how to create sprites, implement movement, handle collisions, and add game logic. This project not only enhances your coding skills but also sparks your creativity. Feel free to experiment with different features, graphics, and sounds to make your game unique. Whether you’re a beginner or an experienced coder, Scratch provides a user-friendly environment to bring your game ideas to life. So go ahead, give it a try, and have fun creating your own version of Slither.io! You got this!